According to Darwin, most suitable driving force for evolution is:

The correct answer is Option (2) → Natural selection

Darwin saw that members of a population differ and that natural resources are limited. Those that are better fitted to the environment leave more progeny, so they survive more and are “selected by nature”. This is natural selection, and it is the essence of Darwin’s theory of evolution.

(1) Industrial melanism — Incorrect. This is an example, not the force. The proportion of dark-winged moths rose after industrialisation because natural selection favoured them.

(2) Natural selection — Correct. It is the mechanism that Darwin gave for evolution.

(3) Genetic drift — Incorrect. This is a change in allele frequency that happens by chance. It is one of the factors that disturb Hardy-Weinberg equilibrium, and it is not Darwin’s driving force.

(4) Genetic recombination — Incorrect. It shuffles alleles during gamete formation and so makes variation. It is also a factor that disturbs Hardy-Weinberg equilibrium, but it is not what Darwin named as the driving force.

NCERT Extract:
Biological Evolution – “… The essence of Darwinian theory about evolution is natural selection.”
Biological Evolution – “… Branching descent and natural selection are the two key concepts of Darwinian Theory of Evolution (Figures 6.7 and 6.8).”